1. Field of the Invention
This invention relates to an image capture device which guides light from a light-emitting element to a subject, to irradiate the subject and capture an image, and in particular relates to an image capture device which is compact and easily assembled.
2. Description of the Related Art
Image capture devices which irradiate a subject with uniform light and capture an image of a prescribed range of the subject are in wide use. Distinct captured images are particularly demanded in image processing systems which use images captured by such image capture devices for image processing.
For example, with advances in biometrics technology in recent years, various devices have been provided which capture images and perform recognition of characteristics of portions of the human body enabling distinction among human beings, such as fingerprints and toe-prints, retina patterns of the eyes, facial features, blood vessel patterns, and similar, to perform authentication of individuals.
In particular, comparatively large quantities of individual characteristic data can be obtained from blood vessels in the palms and backs of the hands and the fingers as well as from palm-prints, so that such data is useful to ensure reliability of individual authentication. Further, the patterns of blood vessels (veins) remain unchanged from infancy throughout life, and are thought to be unique to each individual, making them appropriate for use in individual authentication.
In order to perform such biometrics authentication, contact-free image capture of a subject (for biometrics authentication, a portion of the human body) is necessary. To this end, an image capture device emits light of uniform optical intensity over a certain image capture range (distance and area), uses sensors to receive the light reflected within this image capture range, converts the light into electrical signals, and outputs captured image signals.
As such an image capture device, in the prior art, a configuration has been proposed in which an image capture unit is positioned in the center, and a plurality of light-emitting elements (point-light source elements) are arranged on the periphery thereof (see for example WO2004/088588 (FIG. 1 and FIG. 6)). In this proposal, each of the point-light source elements is responsible for irradiation of a prescribed image-capture range, and so the point-light source elements are positioned on the periphery of and at a distance from the image capture unit, and moreover in order to provide light of prescribed uniform intensity to the image capture range, are positioned in closer proximity to the subject than the image capture unit.
In this image capture device of the prior art, as stated above, the point-light source elements are positioned at a distance, so that the device cannot easily be made compact, and there are limits to incorporation in other equipment. Further, greater compactness results in difficulty of assembly, and the rate of occurrence of defects is high. For these reasons, it has been difficult to realize an image capture device which is small in size and inexpensive.